Method to measure skin elasticity and firmness

Abstract

The invention relates to a method of measuring the elasticity and firmness of skin. The invention also relates to methods of measuring improvements in a person's skin health by measuring firmness and elasticity before, during and after a cosmetic treatment. The invention further relates to methods of measuring the improvement in a person's skin firmness and elasticity that a cosmetic agent may cause when applied on the skin.

What is claimed is: 
     
       1. A method of determining a skin elasticity value for a person's skin, comprising:
 (a)—contacting two parallel metallic plates of a mechanical pinching system on a skin surface zone, recording a first thermal image of the skin surface zone that displays thermal prints of the metallic plates on skin with an infrared thermography imaging apparatus, and measuring a first distance between the two parallel metallic plates on the first thermal image, 
 (b)—after the recording of the first thermal image, pushing at least one of the two parallel metallic plates of the mechanical deformation system toward the other in a direction that is parallel to the skin surface, so as to pinch the skin between the two parallel metallic plates, under a controlled pressure, wherein the two parallel metallic plates remain parallel during the pushing, 
 (c)—releasing the controlled pressure, 
 (d)—after releasing the controlled pressure, recording a second thermal image of the skin surface zone that displays thermal prints of the metallic plates on skin with the infrared thermography imaging apparatus, and measuring a second distance between the two parallel metallic plates on the second thermal image, and 
 (e)—determining a skin elasticity value associated with an elastic recovery of the skin, said skin elasticity value corresponding to the ratio between the second distance and the first distance. 
 
     
     
       2. The method of  claim 1 , wherein in (b), the controlled pressure is between 20 and 40 N. 
     
     
       3. The method of  claim 2 , wherein the skin is considered as having elasticity when the skin elasticity value is higher than 1. 
     
     
       4. The method of  claim 1 , wherein the mechanical deformation system comprises an internal spring and two metallic plates attached to two sliding sections. 
     
     
       5. A method for measuring the effect of a cosmetic product on improving the firmness or elasticity of a person's skin, said method comprising:
 calculating a first value associated with an elastic recovery of the skin sample according to the method of  claim 1 , 
 applying the cosmetic product on the skin sample, 
 calculating a second value associated with an elastic recovery of the skin sample according to the method of  claim 1 , and 
 comparing the first value and the second value. 
 
     
     
       6. The method of  claim 1 , wherein the skin elasticity value corresponds to at least one of determining firmness, tonicity, suppleness, sagging skin, oval of the person's face, bags beneath the person's eyes, nasolabial folds or ptosis of the lower part of the person's face. 
     
     
       7. The method of  claim 1 , wherein the method is conducted on skin of the person's face. 
     
     
       8. The method  claim 1 , wherein the method is conducted on a lower part of the person's cheek. 
     
     
       9. The method of  claim 1 , wherein the pushing of the at least one of the two parallel metallic plates toward the other narrows a space between the two parallel metallic plates; and
 deforms the pinched skin within the space between the two parallel metallic plates; 
 wherein upon releasing the pressure, the pinched skin returns to an unpinched position.